1. Field of the Invention
The invention relates to a needle bar drawing device or gill box for slivers comprising a needle field or gill area of needle bars carried by chains and means for holding down the slivers arranged opposite said needle field, which is arranged between one pair each of entrance and exit rollers, respectively.
2. Description of Prior Art
Such gill boxes are preferably used in processing longstaple spinning material, the lacking upper needle field being substituted by hold down means in the form of slubbing rollers, bar chains or the like. Such structure is essentially preferable in contrast to known double needle bar drawing devices in that the expenses for the construction are lower and it is possible to adjust the nip which is very closely similar to that achievable in spindle driven gill boxes (faller bar devices). The disadvantage of such structure lies in the relatively restricted applicability. In trying to extend the possibilities of application of this construction which, due to the simplicity of its structure, is little susceptible to failure to the production of worsted or mock-worsted material, the meshing conditions were, as e.g. can be taken from DE-GM 74 26 839, adapted to those of double needle bar devices by providing the single needle bars with two needle rows each so that a gill area of a narrower resp. finer needle spacing was achieved. It was found out, however, that the tendency towards lap formation or licking on the exit roller increases considerably, particularly where the spinning material to be treated comprises a large portion of short fibres. This leads to an increased portion of freely-swimming fibres between the needle field and the exit rollers, that is in the so-called nip, which fibres will no longer be carried resp. conveyed safely. The reason for the lap formation resides in that the simultaneous disappearing of two needle rows at the end of the needle field leads to an increased friction between the single fibres and the needles due to the narrow needle division. This phenomenon will also be observed in needle fields with single needle rows of a very fine needle spacing.
3. Object of the Invention
It is therefore a main object of the invention to adapt single row needle bar drawing devices in such a manner that they are suitable for treating short staple or short-fibred spinning material.